1. Field of the Invention
This invention relates to the transfer of materials from one walled enclosure to another without exposing the transferred material to the atmosphere outside the enclosure. More particularly, the invention relates to a port system for allowing such transfer between sterile environments.
2. Description of the Prior Art
In the pharmaceutical manufacturing industry, as well as in other industries such as semiconductor manufacturing, the need frequently arises to transfer sterile material, such as ingredients or equipment, from one sterile environment to another. For example, in some such operations sterile material must be moved from one sterile enclosure to another through a non-sterile environment. In order to preserve the sterility of the material being moved, such an operation is normally carried out by transferring the material from the first enclosure into a transfer container which itself has a sterile interior environment; the transfer container is then moved to the second enclosure and the material transferred from the container to the enclosure. In this specification and the claims following, both the sterile enclosures and the transfer container of this example, as well as other similar structures, are referred to by the general term "walled enclosures."
A major problem in transferring sterile material from the sterile environment in one walled enclosure to that in another has been to provide doors or the like in the enclosure walls which minimize the possibility of contamination from either the outside atmosphere or the non-sterile surfaces of the doors themselves. The prior art includes several approaches to solving this problem, but all suffer from one or more deficiencies. For example, Cruz et al. U.S. Pat. No. 5,275,479 discloses a device and method for transferring objects between two containers while maintaining the sterility of the internal environments of the containers and objects, wherein each container includes a door, formed of Mylar.RTM. film, for abutment against the door of the other container. Once in abutment with one another, the doors are removed to permit transfer of the object. However, the doors of Cruz et al. abut only on their peripheral edges, resulting in a volume of outside air trapped between the doors, and further this device uses a complicated winding system for moving the doors. Cox et al. U.S. Pat. No. 3,097,389 discloses an environmental chamber including an access opening designed to communicate with a corresponding access opening of a container for transferring an object between the chamber and the container while maintaining the sterility of the object and the internal environments of the container and chamber. Both the container and the chamber include respective doors covering the openings which are removed upon connection of the container to the chamber to permit transfer of the object. However, the device of Cox et al. uses a sliding door arrangement in which at least one of the doors is exposed to the outside environment during attachment of the container, thereby preventing further sterile use. Akins U.S. Pat. No. 5,056,875 discloses a system similar to one offered by the French company la Calhene and called "DPTE," in which doors and their frames on the two enclosures are brought together and the doors are mechanically joined and removed from the frames leaving a transfer opening. In order to enable their removal after being joined, the individual door edges are beveled to form a continuous beveled edge in the joined doors, which permits the composite structure to be removed in the direction in which the bevel enlarges the door openings. Such door construction unavoidably includes surfaces, such as the beveled door edges, which cannot be properly cleaned and thus are sources of possible contamination.